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Bug 920292 - <net-misc/openssh-9.6_p1: terrapin vulnerability
Summary: <net-misc/openssh-9.6_p1: terrapin vulnerability
Alias: None
Product: Gentoo Security
Classification: Unclassified
Component: Vulnerabilities (show other bugs)
Hardware: All Linux
: Normal normal (vote)
Assignee: Gentoo Security
Whiteboard: A3 [glsa+]
Depends on: 920725
Blocks: CVE-2023-48795
  Show dependency tree
Reported: 2023-12-18 23:45 UTC by Christopher Fore
Modified: 2024-01-07 05:52 UTC (History)
5 users (show)

See Also:
Package list:
Runtime testing required: ---


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Description Christopher Fore 2023-12-18 23:45:26 UTC
CVE-2023-48795 (

The SSH transport protocol with certain OpenSSH extensions, found in OpenSSH before 9.6 and other products, allows remote attackers to bypass integrity checks such that some packets are omitted (from the extension negotiation message), and a client and server may consequently end up with a connection for which some security features have been downgraded or disabled, aka a Terrapin attack. This occurs because the SSH Binary Packet Protocol (BPP), implemented by these extensions, mishandles the handshake phase and mishandles use of sequence numbers. For example, there is an effective attack against ChaCha20-Poly1305 (and CBC with Encrypt-then-MAC). The bypass occurs in and (if CBC is used) the MAC algorithms. This also affects Maverick Synergy Java SSH API before 3.1.0-SNAPSHOT, Dropbear through 2022.83, Ssh before 5.1.1 in Erlang/OTP, and PuTTY before 0.80; and there could be effects on Bitvise SSH through 9.31, AsyncSSH through 2.14.1, libssh through 0.10.5, and through 2023-12-17.
Comment 1 Larry the Git Cow gentoo-dev 2023-12-19 05:42:36 UTC
The bug has been referenced in the following commit(s):

commit d1307b9e32ea830c31939a8083de2b052e6fa3bc
Author:     Sam James <>
AuthorDate: 2023-12-19 05:40:50 +0000
Commit:     Sam James <>
CommitDate: 2023-12-19 05:40:50 +0000

    net-misc/openssh: add 9.6_p1
    Signed-off-by: Sam James <>

 net-misc/openssh/Manifest              |   2 +
 net-misc/openssh/openssh-9.6_p1.ebuild | 378 +++++++++++++++++++++++++++++++++
 2 files changed, 380 insertions(+)
Comment 2 Larry the Git Cow gentoo-dev 2023-12-20 07:14:49 UTC
The bug has been referenced in the following commit(s):

commit 0b22d07f89b16ac3400e45077702ac4c4492e5a4
Author:     Sam James <>
AuthorDate: 2023-12-20 07:12:26 +0000
Commit:     Sam James <>
CommitDate: 2023-12-20 07:14:16 +0000

    net-misc/openssh: disable problematic -fzero-call-used-regs=*
     --with-hardening adds the following in addition to flags we
     already set in our toolchain:
     * -ftrapv (which is broken with GCC anyway),
     * -ftrivial-auto-var-init=zero (which is nice, but not the end of
        the world to not have)
     * -fzero-call-used-regs=used (history of miscompilations with
        Clang (bug #872548), ICEs on m68k (bug #920350, gcc PR113086,
        gcc PR104820, gcc PR104817, gcc PR110934)).
     Furthermore, OSSH_CHECK_CFLAG_COMPILE does not use AC_CACHE_CHECK,
     so we cannot just disable -fzero-call-used-regs=used.
     Therefore, just pass --without-hardening, given it doesn't negate
     our already hardened toolchain defaults, and avoids adding flags
     which are known-broken in both Clang and GCC and haven't been
     proven reliable.
    Signed-off-by: Sam James <>

 net-misc/openssh/openssh-9.6_p1-r1.ebuild | 396 ++++++++++++++++++++++++++++++
 1 file changed, 396 insertions(+)
Comment 3 Larry the Git Cow gentoo-dev 2023-12-28 02:22:16 UTC
The bug has been referenced in the following commit(s):

commit 3dfe782899716a3480c9481c69bca8c231c663a7
Author:     GLSAMaker <>
AuthorDate: 2023-12-28 02:21:28 +0000
Commit:     Sam James <>
CommitDate: 2023-12-28 02:22:09 +0000

    [ GLSA 202312-17 ] OpenSSH: Multiple Vulnerabilities
    Signed-off-by: GLSAMaker <>
    Signed-off-by: Sam James <>

 glsa-202312-17.xml | 45 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)